1. Field of the Invention
The present invention relates to an image processing apparatus, a method of controlling the image processing apparatus, and a program executing the image processing method, a storage medium program, and a storage medium.
2. Description of the Related Art
The technology referred to as “super-resolution processing and super resolution conversion”, which allows for increasing a resolution by using image data with a predetermined resolution by as much as a plurality of frames, has been available. The use of the above-described technology allows for converting a low-resolution image into a high-resolution image and obtaining a high-resolution image through a known device (“Super Resolution Processing by Plural Number of Lower Resolution Images” (Ricoh Technical Report No. 24, November 1998)).
For performing the super-resolution technology, data items of an original image should be prepared, the image data items corresponding to a plurality of frames. The original-image reading positions of the individual image data items are a little different from one another on a scale measured in sub pixels (the sub pixel is smaller than a single pixel). Therefore, the super-resolution technology is widely used in the area of video processing or the like.
However, for performing the super-resolution processing, image data should be prepared by as much as a plurality of frames, so as to generate the image corresponding to a single pixel of a high-resolution image. Consequently, the data amount and the calculation amount are increased.
In the past, therefore, the number of frames for which the super-resolution processing is performed is determined based on the size of an image area of interest so that the calculation amount is decreased, as disclosed in Japanese Patent Laid-Open No. 2006-092450.
However, the number of images for which the super-resolution processing is performed is determined only for the area of interest according to the above-described known technology. Therefore, the number of frame-image data items that should be prepared for performing the super-resolution processing should be obtained on the entire image area in advance.
Further, when the super-resolution processing is used for a multifunction peripheral (MFP) which is an image processing apparatus, line sensors are usually used as a reader provided in the MFP, a scanner, and so forth.
That is to say, a single read frame is obtained through a single read operation. According to the above-described reader, an original image is read through groups of pixel sensors that are horizontally arranged in the main scanning direction with distances therebetween, the value of each of the distances corresponds to an integer multiple of the pixel. It is difficult for the above-described reader to read the original image while providing shifts that are as small as a sub pixel between the positions where the original image is read in the main scanning direction.
Therefore, an area sensor is installed in the image processing apparatus, so as to be inclined from a reference installation position, frame image data can be acquired through a single read operation, while the positions of pixels for reading are little shifted from one another in the main scanning direction and/or the sub scanning direction. In that case, however, low-resolution frame image data corresponding to a plurality of read frames is used irrespective of conditions for outputting image data. Therefore, it is often difficult to reproduce an output image with a demanded quality based on the read low-resolution frame image data.